Highly alternating ethylene styrene interpolymers

ABSTRACT

Novel ethylene styrene interpolymers having atactic ES repeating units and an alternating structure substantially higher than that predicted using Bernoullian statistics may be prepared in the presence of a transition metal phosphinimine compound and an activator.

FIELD OF THE INVENTION

[0001] The present invention relates to interpolymers (includingcopolymers) of ethylene with one or more C₈₋₂₀ vinyl aromatic monomers,which polymers have a highly alternating structure. That is the polymerhas to the extent possible a structure of alternating ethylene and thevinyl aromatic monomers.

BACKGROUND OF THE INVENTION

[0002] Polymers of one or more alpha olefins are generally incompatiblewith polymers of one or more C₈₋₂₀ vinyl aromatic monomers. As a result,it is difficult to blend or even laminate, for example polystyrene andpolyethylene. There have been a number of attempts to prepare copolymersof, for example styrene and ethylene. Such polymers could lead to twodifferent developments. The copolymer might have the properties soughtafter in the blend or the copolymer may be a suitable compatibilizer sothat the blend could be prepared.

[0003] U.S. Pat. No. 6,066,709 issued May 23, 2000 assigned to DenkiKagaku Kogyo Kabushiki Kaisha discloses an ethylene styrene copolymerhaving from 1 to 55 mole % of an isotactic ES structure having a head totail bond structure (e.g. ESSE). The polymers of the present inventionhave ¹³C NMR peaks at 25.7 indicating an atactic structure rather thanisotactic structure.

[0004] U.S. Pat. No. 6,191,245 issued Feb. 20, 2001 to Campbell et al.,assigned to the Dow Chemical Company teaches copolymers of one or morealpha olefins and one or more vinyl aromatic monomers which aresubstantially random (Col. 6 lines 45-48). The polymers of the presentinvention have a significantly higher degree of alternating structurethan that predicted by Bernoullian statistical modeling. The ratio ofthe amount of triads having the sequence vinyl aromatic monomer,ethylene, vinyl aromatic monomer divided by the calculated amount oftriads having the same sequence as determined by Bernoullian statisticalmodeling is from greater than 1.5 to 9.5.

[0005] U.S. Pat. No. 5,703,187 issued Dec. 30, 1997, assigned to the DowChemical Company teaches pseudo random co-polymers of styrene andethylene. The specification teaches a particular distinguishing featureof pseudo random copolymers is that all the phenyl groups substituted onthe polymer backbone are separated by 2 or more methylene units. Nostyrene was inserted in a head to tail manner. The polymers of the Dowpatent do not have the high degree of alternating nature of the polymersof the present invention. Additionally, the process for preparing suchpolymers uses a catalyst distinct from that disclosed in the reference.

[0006] U.S. Pat. No. 6,191,245 B1 filed by the Dow Chemical Companyclaims a substantially random structure of an ethylene styrene copolymerwith a head to tail insertion. The reference teaches that the styrene inthe styrene ethylene tetrad (ESSE) is inserted exclusively in the headto tail manner. The patent teaches away from ES in an alternatingstructure.

[0007] There are a number of Idemitsu Kosan Co. Ltd. patents which teachpolymers comprising blocks of syndiotactic polystyrene (the phenyl ringsare alternating on opposite sides of the back bone) and the olefin isincorporated in repeating units (e.g. olefin blocks). The patent teachesblocks of syndiotactic polystyrene and does not suggest ES in analternating structure. Additionally, the process for preparing the blockcopolymers does not use the catalyst system contemplated by the presentinvention.

[0008] U.S. Pat. No. 5,043,408 issued Aug. 27, 1991 teaches an ethylenestyrene copolymer having alternating ES units. However, the polymer hasan isotactic diad of the ES repeating units of not less than 0.55 (i.e.greater than 0.55). The polymers of the present invention areessentially atactic ES having head to tail and tail to tail SSmicrostructure.

[0009] U.S. Pat. No. 6,235,855 issued May 22, 2001 teaches an ES polymerhaving isotactic styrene blocks. The alternating polymer of the presentinvention contains not more than two styrene monomers in a row andconsequently does not contain polystyrene blocks.

[0010] The present invention seeks to provide a highly alternatingpolymer comprising ethylene and one or more vinyl aromatic monomers inwhich, in the triad sequence of vinyl aromatic monomer and ethylene asdetermined by ¹³C NMR, the triads have the sequence vinyl aromaticmonomer, ethylene, vinyl aromatic monomer and the ratio of the amount oftriads having the sequence vinyl aromatic monomer, ethylene, vinylaromatic monomer divided by the calculated amount of triads having thesame sequence, as determined by Bernoullian statistical modeling, isfrom greater than 1.5 to 9.5.

SUMMARY OF THE INVENTION

[0011] The present invention provides a highly alternating interpolymerconsisting of from 20 to 70 weight % of ethylene and from 80 to 30weight % a C₈₋₂₀ vinyl aromatic monomer wherein:

[0012] (i) in the triad sequence of vinyl aromatic monomer and ethyleneas determined by ¹³C NMR, the triads have the sequence vinyl aromaticmonomer, ethylene, vinyl aromatic monomer and the ratio of the amount oftriads having the sequence vinyl aromatic monomer, ethylene, vinylaromatic monomer divided by the calculated amount of triads having thesame sequence as determined by Bernoullian statistical modeling is fromgreater than 1.5 to 9.5;

[0013] (ii) said polymer has ES repeating units essentially in anatactic configuration;

[0014] (iii) the maximum number of sequential vinyl aromatic monomerunits in sequence does not exceed 2; and

[0015] (iv) said polymer containing ES repeating unit, having head totail and tail to tail SS microstructure present.

[0016] The present invention further provides a process for preparingthe above highly alternating interpolymer, comprising contacting amonomer mixture comprising from 70 to 30 weight % of a C₈₋₂₀ vinylaromatic monomer and from 30 to 70 weight % of ethylene with a catalystcomprising a phosphinimine compound of the formula:

L′((R¹)₃P═N)—M—L₂

[0017] wherein each R¹ is independently selected from the groupconsisting of C₃₋₆ alkyl radicals, M is selected from the groupconsisting of Ti, Zr and Hf, and each L is independently selected fromthe group consisting of a halogen atom, a hydrogen atom, a C₁₋₁₀ alkylradical, a C₁₋₁₀ alkoxide radical, and a C₆₋₁₀ aryl oxide radical, L′ isan anionic ligand having up to 50 C, H, O, N, Si and P atoms and atleast one activator selected from the group consisting of:

[0018] (i) a mixture comprising complex aluminum compound of the formulaR² ₂AlO(R²AlO)_(m)AlR² ₂ wherein each R² is independently selected fromthe group consisting of C₁₋₂₀ hydrocarbyl radicals and m is from 3 to50, and a hindered phenol to provide a molar ratio of Al:hindered phenolfrom 2:1 to 5:1; and

[0019] (ii) ionic activators selected from the group consisting of:

[0020] (A) compounds of the formula [R³]⁺ [B(R⁴)₄]⁻ wherein B is a boronatom, R³ is a cyclic C₅₋₇ aromatic cation or a triphenyl methyl cationand each R⁴ is independently selected from the group consisting ofphenyl radicals which are unsubstituted or substituted with from 3 to 5substituents selected from the group consisting of a fluorine atom, aC₁₋₄ alkyl or alkoxy radical which is unsubstituted or substituted by afluorine atom; and a silyl radical of the formula —Si—(R⁵)₃; whereineach R⁵ is independently selected from the group consisting of ahydrogen atom and a C₁₋₄ alkyl radical; and

[0021] (B) compounds of the formula [(R⁸)_(t)ZH]⁺[B(R⁴)₄]⁻ wherein B isa boron atom, H is a hydrogen atom, Z is a nitrogen atom or phosphorusatom, t is 2 or 3 and R⁸ is selected from the group consisting of C₁₋₈alkyl radicals, a phenyl radical which is unsubstituted or substitutedby up to three C₁₋₄ alkyl radicals, or one R⁸ taken together with thenitrogen atom may form an anilinium radical and R⁴ is as defined above;and

[0022] (C) compounds of the formula B(R⁴)₃ wherein R⁴ is as definedabove;

[0023] (iii) mixtures of (i) and (ii); in an inert hydrocarbyl medium ata temperature from 20° C. to 150° C. and a pressure from 15 psi (103KPa) to 600 psi (4,137 KPa).

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a ¹³C NMR spectrum of the ethylene styrene interpolymerproduced according to Example 1 after MEK extraction.

DETAILED DESCRIPTION

[0025] For the purposes of this specification a ¹³C NMR peak means asignal that is at least three times the peak to peak noise.

[0026] The present invention relates to highly alternating polymers ofethylene and one or more C₈₋₂₀, preferably C₈₋₁₂, vinyl aromaticmonomers which are unsubstituted or substituted by a C₁₋₄ alkyl radical.The vinyl aromatic monomer may be selected from the group consisting ofstyrene, alpha methyl styrene and p-methyl styrene. Preferably, thevinyl aromatic monomer is styrene.

[0027] The polymers of the present invention generally comprise from 20to 70, preferably from 30 to 70, most preferably from 30 to 60 weight %of ethylene and from 80 to 30, preferably from 70 to 30, most preferablyfrom 70 to 40 weight % of vinyl aromatic monomer. The polymers of thepresent invention generally do not contain a ¹³C NMR peak at a shift(relative to TMS) of about 40.8 to 41.0 ppm (syndiotactic) or 40.5 to41.0 ppm (atactic blocks). Carbon-13 NMR spectra of the polymers do nothave a peak near 40 to 41 ppm indicating no isotactic configuration. The¹³C NMR spectra also have small peaks at about 34 to 34.5 ppm and 34.5to 35.2 ppm, generally attributed to pseudo block portions (styrene tailto tail insertion) of the polymer.

[0028] Triad sequence distributions were determined from methine ormethylene resonances for ESE, SES, SEE and EEE triads located at 46.5ppm, 25.7 ppm, 27.9 ppm and 30.0 ppm respectively. Styrene-styreneinversions were determined from the methylene resonances observedbetween 34 and 36 ppm. Peak areas were used to calculate the normalizedtriads per 1000 backbone carbons according to the formula below.

[triad]=(A1/n1)×1000/A[backbone]

[0029] where A1 is the peak area for the resonance representing thetriad, n1 is the number of carbons per unit triad contributing to thepeak area, A1, and A[backbone] represents the sum of the areas for peaksattributable to the main chain carbon backbone.

[0030] SES from Bernoullian statistical modeling is calculated asdescribed by J. C. Randall in POLYMER SEQUENCE DETERMINATION, CARBON-13NMR METHOD, Academic Press New York, 1977, pp 71-78.

[0031] Tacticity of ethylene-styrene repeating unit was determined bythe Sββ resonance of ethylene-styrene alternating sequences appearing atabout 25 ppm. The meso and racemic diads of this sequence havepreviously been described in the literature. (Suzuki, T.; Tsuji, Y.;Watanabe, Y.; Takegami, T. Macromolecules, 13, 849 (1980); Kakugo M.;Miyatake, T.; Mizunuma, K. Studies in Surface Science and Catalysis, 56,517 Kodansha Ltd (Tokyo)/Elsevier (Amsterdam) 1990; Pellecchia, C;Pappalardo, D; D'Arco, M.; Zambelli, A. Macromolecules, 29, 1158-1162(1996); Arai, T; Ohtsu, T.; Suzuki, S. Macromol Rapid Commun, 19,327-331 (1998); and U.S. Pat. No. 6,066,709.

[0032] GRAMS/32 software (Galactic Industries) was used to curvefit thisresonance to obtain the relative areas for the meso and racemic diads.Within experimental error, we obtained equal amounts of m and r diads,confirming the atactic structure of ethylene and styrene repeating unit.

[0033] In the polymers of the present invention, preferably the ratio ofthe amount of triads having the sequence vinyl aromatic monomer,ethylene, vinyl aromatic monomer divided by the calculated amount oftriads having the same sequence as determined by Bernoullian statisticalmodeling is greater than 1.5 to 9.5, preferably from 6 to 9.5, mostpreferably from 6.5 to 8.5. Preferably, not less than 57%, mostpreferably not less than 55% of the ethylene and vinyl aromatic monomeravailable to form triads, form triads having the sequence vinyl aromaticmonomer, ethylene, vinyl aromatic monomer and less than 10% of themonomer available, form vinyl aromatic monomer diads.

[0034] The polymers of the present invention may be prepared by solutionor slurry polymerization of the monomers in the presence of a catalystcomprising a phosphinimine compound of the formula:

L′((R¹)₃P═N)—M—L₂

[0035] wherein each R¹ is independently selected from the groupconsisting of C₃₋₆ alkyl radicals, M is selected from the groupconsisting of Ti, Zr and Hf, and each L is independently selected fromthe group consisting of a halogen atom, a hydrogen atom, a C₁₋₁₀ alkylradical, a C₁₋₁₀ alkoxide radical, and a C₆₋₁₀ aryl oxide radical, L′ isan anionic ligand having up to 50 C, H, O, N, Si and P atoms and atleast one activator selected from the group consisting of:

[0036] (i) a mixture comprising complex aluminum compound of the formulaR² ₂AlO(R²AlO)_(m)AlR² ₂ wherein each R² is independently selected fromthe group consisting of C₁₋₂₀ hydrocarbyl radicals and m is from 3 to50, and a hindered phenol to provide a molar ratio of Al:hindered phenolfrom 2:1 to 5:1; and

[0037] (ii) ionic activators selected from the group consisting of:

[0038] (A) compounds of the formula [R³]⁺ [B(R⁴)₄]⁻ wherein B is a boronatom, R³ is a cyclic C₅₋₇ aromatic cation or a triphenyl methyl cationand each R⁴ is independently selected from the group consisting ofphenyl radicals which are unsubstituted or substituted with from 3 to 5substituents selected from the group consisting of a fluorine atom, aC₁₋₄ alkyl or alkoxy radical which is unsubstituted or substituted by afluorine atom; and a silyl radical of the formula —Si—(R⁵)₃; whereineach R⁵ is independently selected from the group consisting of ahydrogen atom and a C₁₋₄ alkyl radical; and

[0039] (B) compounds of the formula [(R⁸)_(t)ZH]⁺[B(R⁴)₄]⁻ wherein B isa boron atom, H is a hydrogen atom, Z is a nitrogen atom or phosphorusatom, t is 2 or 3, and R⁸ is selected from the group consisting of C₁₋₈alkyl radicals, a phenyl radical which is unsubstituted or substitutedby up to three C₁₋₄ alkyl radicals, or one R⁸ taken together with thenitrogen atom may form an anilinium radical and R⁴ is as defined above;and

[0040] (C) compounds of the formula B(R⁴)₃ wherein R⁴ is as definedabove; and

[0041] (iii) mixtures of (i) and (ii); in an inert hydrocarbyl medium ata temperature from −40° C. to 160° C., preferably from 20° C. to 150° C.and a pressure from 15 psi to 15,000 psi, preferably from 15 psi to 600psi. The polymerization may take place at temperatures from about 20° C.to about 150° C., most preferably from about 60° C. to about 120° C. andat pressures from about 15 psi (103 KPa) up to about 600 psi (4,137KPa), most preferably from about 100 psi (689 KPa) to 600 psi.

[0042] The polymerization may be conducted in the presence of an inertsolvent or diluent. Suitable solvents or diluents are hydrocarbonshaving from about 5 to 12 carbon atoms or mixtures thereof. Thesecompounds include pentane, hexane, heptane, octane, cyclohexane,methylcyclohexane, benzene, toluene, and hydrogenated naphtha. Acommercially available hydrocarbon is ISOPAR® (a C₅₋₁₂ aliphatic solventsold by EXXON Chemical Co.).

[0043] In the phosphinimine complex preferably, wherein R¹ is a C₃₋₅branched alkyl radical (e.g. isopropyl, isobutyl, t-butyl, etc.), L isselected from the group consisting of a hydrogen atom, a chlorine atomand a C₁₋₄ alkyl radical, L′ is a phosphinimine, siloxy, amide and M isTi. If L′ is a phosphinimine ligand it may be the same or different fromthe phosphinimine ligand already in the complex. Suitable siloxy ligandsinclude tri-C₁₋₆ alkyl siloxy ligands, preferably the alkyl substituenthas from 3 to 5 carbons atoms and may be branched or straight chained,most preferably branched. Suitable amide ligands are dialkyl amidescontaining up to 12 carbon atoms in which the alkyl substituents may bejoined to (or taken together) form a ring which is unsubstituted orfurther substituted by up to 3 C₁₋₃ alkyl radicals. A suitable amideligand is 2,2,6,6-tetra methyl piperidinyl.

[0044] In the aluminum compound, preferably R² is a methyl radical and mis from 10 to 40. The preferred molar ratio of Al:hindered phenol isfrom 3.25:1 to 4.50:1. Preferably the phenol is substituted in the 2, 4and 6 position by a C₂₋₆ alkyl radical. Desirably the hindered phenol is2,6-di-tert-butyl-4-ethyl-phenol.

[0045] The “ionic activator” may abstract one or more activatableligands so as to ionize the catalyst center into a cation, but not tocovalently bond with the catalyst and to provide sufficient distancebetween the catalyst and the ionizing activator to permit apolymerizable olefin to enter the resulting active site.

[0046] Examples of ionic activators include:

[0047] triethylammonium tetra(phenyl)boron,

[0048] tripropylammonium tetra(phenyl)boron,

[0049] tri(n-butyl)ammonium tetra(phenyl)boron,

[0050] trimethylammonium tetra(p-tolyl)boron,

[0051] trimethylammonium tetra(o-tolyl)boron,

[0052] tributylammonium tetra(pentafluorophenyl)boron,

[0053] tripropylammonium tetra(o,p-dimethylphenyl)boron,

[0054] tributylammonium tetra(m,m-dimethylphenyl)boron,

[0055] tributylammonium tetra(p-trifluoromethylphenyl)boron,

[0056] tributylammonium tetra(pentafluorophenyl)boron,

[0057] tri(n-butyl)ammonium tetra(o-tolyl)boron,

[0058] N,N-dimethylanilinium tetra(phenyl)boron,

[0059] N,N-diethylanilinium tetra(phenyl)boron,

[0060] N,N-diethylanilinium tetra(phenyl)n-butylboron,

[0061] di-(isopropyl)ammonium tetra(pentafluorophenyl)boron,

[0062] dicyclohexylammonium tetra(phenyl)boron,

[0063] triphenylphosphonium tetra(phenyl)boron,

[0064] tri(methylphenyl)phosphonium tetra(phenyl)boron,

[0065] tri(dimethylphenyl)phosphonium tetra(phenyl)boron,

[0066] tropillium tetrakispentafluorophenyl borate,

[0067] triphenylmethylium tetrakispentafluorophenyl borate,

[0068] tropillium phenyltrispentafluorophenyl borate,

[0069] triphenylmethylium phenyltrispentafluorophenyl borate,

[0070] benzene (diazonium) phenyltrispentafluorophenyl borate,

[0071] tropillium tetrakis (2,3,5,6-tetrafluorophenyl) borate,

[0072] triphenylmethylium tetrakis (2,3,5,6-tetrafluorophenyl) borate,

[0073] tropillium tetrakis (3,4,5-trifluorophenyl) borate,

[0074] benzene (diazonium) tetrakis (3,4,5-trifluorophenyl) borate,

[0075] tropillium tetrakis (1,2,2-trifluoroethenyl) borate,

[0076] triphenylmethylium tetrakis (1,2,2-trifluoroethenyl) borate,

[0077] tropillium tetrakis (2,3,4,5-tetrafluorophenyl) borate, and

[0078] triphenylmethylium tetrakis (2,3,4,5-tetrafluorophenyl) borate.

[0079] Readily commercially available ionic activators include:

[0080] N,N-dimethylaniliniumtetrakispentafluorophenyl borate;

[0081] triphenylmethylium tetrakispentafluorophenyl borate(tritylborate); and

[0082] trispentafluorophenyl borane.

[0083] The aluminum compounds (alumoxanes) are typically used insubstantial molar excess compared to the amount of metal in thecatalyst. Aluminum:transition metal molar ratios of from 10:1 to10,000:1 are preferred, especially from 50:1 to 500:1.

[0084] Another type of activator is the “ionic activator” or“substantially non-coordinating anion”. As used herein, the termsubstantially non-coordinating anions (“SNCA”) are well known cocatalystor activator systems which are described, for example, in U.S. Pat. No.5,153,157 (Hlatky and Turner), and the carbonium, sulfonium and oxoniumanalogues of such activators which are disclosed by Ewen in U.S. Pat.No. 5,387,568. In general, these SNCA form an anion which only weaklycoordinates to a cationic form of the catalyst.

[0085] While not wanting to be bound by theory, it is generally believedthat SNCA-type activators ionize the catalyst by abstraction orprotonation of one of the “X” ligands (non-interfering ligands) so as toionize the group 4 metal center into a cation (but not to covalentlybond with the group 4 metal) and to provide sufficient distance betweenthe ionized group 4 metal and the activator to permit a polymerizableolefin to enter the resulting active site. It will be appreciated bythose skilled in the art that it is preferable that the“non-interfering” (“X”) ligands be simple alkyls when using a SNCA asthe activator. This may be achieved by the alkylation of a halide formof the catalyst.

[0086] If the phosphinimine compound is activated only with the ionicactivator the molar ratio of transition metal to boron will be from 1:1to 1:3 preferably from 1:1.05 to 1:1.20.

[0087] In a preferred embodiment of the present invention the catalystis a combination of a phosphinimine compound, an aluminum compound witha hindered phenol and an ionic activator. Generally such a catalystsystem has a molar ratio of transition metal (e.g. Ti):Al:boron from1:20:1 to 1:120:3, preferably 1:20:1 to 1:45:1.5, most preferably from1:38:1 to 1:42:1.5.

[0088] The resulting polymer is then recovered and separated from thesolvent and then devolatilized using conventional techniques.

[0089] The resulting polymer typically will have a molecular weight(weight average Mw) from about 100,000 to about 400,000. The polymer maybe compounded with conventional heat and light stabilizers(antioxidants) and UV stabilizers in conventional amounts. Typically theantioxidant may comprise a hindered phenol and a secondary antioxidant,generally in a weight ratio of about 0.5:1 to 5:1 and the total amountof antioxidant may be from 200 to 3,000 ppm. Generally, the UVstabilizer may be used in amounts from 100 to 1,000 ppm.

[0090] The present invention will now be illustrated by the followingnon-limiting examples in which unless otherwise specified parts meansparts by weight (e.g. grams) and % means weight percent.

[0091] The ethylene and styrene polymerization reactions were performedin a 2 L Parr reactor. All the chemicals (solvent, comonomers, catalystand scavenger) were fed into the reactor batchwise except ethylene,which was fed on demand. The ethylene was controlled using a Hastingmass flow controller set at a maximum rate of 10 slpm (standard literper minute). As are known to those skilled in the art, all the feedstreams were purified prior to feeding into the reactor by contact withvarious absorption media to remove catalyst-killing impurities such aswater, oxygen, sulfur and polar materials. A purification column packedwith DD-2 alumina from Alcoa was used to remove the inhibitor instyrene. Passing the styrene through the column was found to reduce thecatechol concentration to less than 1 ppm and the moisture to ˜10 ppm.All reaction components were stored and manipulated under an atmosphereof purified nitrogen or argon. Purified hexane was used as the solventfor the reaction. The reaction was monitored using the Labtech Notebooksoftware. Temperature control was achieved through the use of anautomated temperature control system.

[0092] PMAO-IP was purchased from Akzo-Nobel with 12.7 weight % ofaluminum. [CPh₃][B(C₆F₅)₄] was purchased from Asahi Glass Inc.; lot #:980224. Hexane was purchased from Aldrich as HPLC grade and purified bycontact with various absorption media. Toluene was purchased fromAldrich and purified by passing through various absorption media.Toluene was used as a dilution solvent for catalyst/cocatalyst. Styrenewas obtained from NOVA Chemical's internal styrene plant with about 15ppm of t-butyl catechol. 5-ethylidene-2-norbornene (ENB) was purchasedfrom Aldrich and distilled over CaH₂ and stored over molecular sieves at−35° C. 1-octene was purified by contact with various absorption media.Hydrogen and ethylene were purchased from Praxair as UHP and polymergrade, respectively. (NPtBu₃)₂TiCl₂/(NPtBu₃)₂TiMe₂ was preparedaccording to the procedure disclosed in the WO 00005238 Al (U.S. Pat.No. 6,239,238). MAO solution: PMAO-IP and 2,6-di-t-butyl-4 ethyl-phenolwere dissolved in toluene with Al/phenol=3.25.

[0093] The polymerization temperatures for styrene and ethylenereactions were set at 90° C. 500 ml of styrene was added into thereactor as a batch. The total reaction pressure was 100 psig at 90° C.400 ml of hexane was used as reaction diluent. The reaction time was 60minutes or until the ethylene consumption reached 60 L. The reactionswere terminated by adding 5 ml of methanol. The polymer solution wascollected in a stainless steel bowl and was treated in a water bath at100° C. to remove unreacted styrene and solvent. The ES polymers werethen dried in a vacuum oven for at least 4 hours at about 80° C.Polymerization activities were calculated based on the weight of thepolymer produced, the concentration of catalyst and the duration ofreaction.

[0094] ES methyl ethyl ketone (MEK) soluble and insoluble fractionsdetermination: 1 g of ES copolymer was dissolved in 15 ml of toluene atroom temperature overnight. The solution was heated to 100° C. for 1-2hours, then cooled to 60° C. 300 ml of MEK was added. The solution wascooled to −74° C. overnight. MEK soluble and insoluble fractions werethen separated and collected for further analysis.

[0095] FT-IR analysis was conducted using a Nicolet Model 750 Magna IRspectrometer.

[0096] I₂ was measured with 2.16 kg at 190° C. using a Tinius OlsenMP993.

[0097] Polymers were analyzed by ¹³C NMR spectroscopy at 125° C. using aBruker DPX300 spectrometer operating at 75.47 MHz. All samples were MEKinsoluble fractions and were prepared at 5-15 weight % in 10 mm NMRtubes using 1,1,2,2-tetrachloroethane-d2 as the lock solvent. Thespectrometer was operated using the following parameters: spectralwidth, 15,000 Hz; pulse width, 90°; acquisition time, 2.72 seconds;delay, 7.28 seconds; decoupling, bilevel composite pulse decoupling;file size, 64K data points; line broadening, 1-2 Hz; number of scans,8000.

[0098] Chemical shifts are based on the isolated methylene backboneresonance occurring at 30.0 ppm versus TMS. This was achieved byreferencing the central peak of the 1,1,2,2-tetrachloroethane-d2 to 74.4ppm. Distortionless Enhanced Polarization Transfer (DEPT) experimentswere performed using a standard DEPT-135 pulse sequence. All methyl andmethine carbons appeared as positive peaks while the methylene carbonsgenerated negative peaks.

[0099] Preparation of Ethylene and Styrene Interpolymers

EXAMPLE 1

[0100] Polymerization was carried out by using a 2L Parr reactorequipped with a stirrer and a jacket for heating/cooling. 400 ml of dryhexane and 500 ml of dry styrene were charged along with 27 mmol of MAOsolution into the reactor. The inner temperature was raised to 90° C.with stirring. Ethylene was introduced to maintain 100 psig during thepolymerization reaction. About 4 ml of a toluene solution containing amixture of (NPtBU₃)₂TiMe₂ (58.5 umol), [CPh₃][B(C₆F₅)₄] (87.8 umol) andMAO solution (1.17 mmol of Al) was added to the reactor from a catalysttank installed above the reactor. The temperature increased to over 100°C. initially and was brought back to 90° C. within 5 minutes by thecooling system. Polymerization was carried out for 1 hour. After thepolymerization, 5 ml of methanol was injected into the reactor to stopthe reaction. The obtained polymer solution was treated in a water bathto remove unreacted styrene and solvent. 500 ppm of antioxidant(Irganox-1076) was added. Polymer was dried under reduced pressure at80° C. until no weight change was observed.

EXAMPLE 2

[0101] Polymerization and post treatment were carried out in the samemanner as in Example 1 under the conditions shown in Table1. This is arepeating experiment with half of the catalyst concentration.

EXAMPLE 3

[0102] Polymerization and post treatment were carried out in the samemanner as in Example 1 under the conditions shown in Table1, except Δ5psig of H₂ was introduced through a 150 ml shot tank at 200 psig of H₂.

EXAMPLES 4 and 5

[0103] Polymerization and post treatment were carried out in the samemanner as in Example 1 under the conditions and catalyst system shown inTable1.

EXAMPLE 6

[0104] Polymerization and post treatment were carried out in the samemanner as in Example 1 under the conditions and catalyst system shown inTable1, except 10 ml of ENB was added to the reactor.

COMPARATIVE EXAMPLE 7

[0105] Polymerization and post treatment were carried out in the samemanner as in Example 1 under the conditions and catalyst system shown inTable1. TABLE 1 Amount of Activity g Ex. Catalyst Yield Polymer/ #Catalyst/Cocatalyst (umol/L) (g) mmolCat*hr 1 (NPtBu₃)₂TiMe₂/  65 1041753 Tritylborate 2 (NPtBu₃)₂TiMe₂/  32  66 2369 Tritylborate 3(NPtBu₃)₂TiMe₂/  74 107 1571 Tritylborate¹ 4 (NPtBu₃)₂TiCl₂/MAO 100 1942089 Solution² 5 (NPtBu₃)₂TiCl₂/MAO 100 110 2437 Solution/Tritylborate³6 (NPtBu₃)₂TiCl₂/MAO  50  46 1000 Solution⁴ 7 Dow—CGC—Me₂ +  65 147 2418PMAO—IP/B(C₆F₅)₃ ⁵

[0106] TABLE 2 Ex. St Content [SES]_(E)/ I₂ MEK Soluble # (wt %)[SES]_(B) (g/10 min) (wt %) 1 66 8.3 0.4 17 2 67 7.2 1.9 15 3 69 — 20.7 — 4 72 7.4 36.1  48 5 69 7.1 1.1 11 6 73 6.8 0.7 17 7 57 4.9 4.2 16

What is claimed is:
 1. A highly alternating interpolymer consisting offrom 20 to 70 weight % of ethylene and from 80 to 30 weight % a C₈₋₂₀vinyl aromatic monomer wherein: (i) in the triad sequence of vinylaromatic monomer and ethylene as determined by ¹³C NMR, the triads havethe sequence vinyl aromatic monomer, ethylene, vinyl aromatic monomerand the ratio of the amount of triads having the sequence vinyl aromaticmonomer, ethylene, vinyl aromatic monomer divided by the calculatedamount of triads having the same sequence as determined by Bernoullianstatistical modeling is from greater than 1.5 to 9.5; (ii) said polymerhas ES repeating units essentially in an atactic configuration; (iii)the maximum number of sequential vinyl aromatic monomer units insequence does not exceed 2; and (iv) said polymer containing ESrepeating unit, having head to tail and tail to tail SS microstructurepresent.
 2. The highly alternating interpolymer according to claim 1,wherein the vinyl aromatic monomer is a C₈₋₁₂ vinyl aromatic monomer. 3.The highly alternating interpolymer according to claim 2, wherein theC₈₋₁₂ vinyl aromatic monomer is selected from the group consisting ofstyrene, alpha methyl styrene and para-methyl styrene.
 4. The highlyalternating interpolymer according to claim 3, wherein the ratio of theamount of triads having the sequence vinyl aromatic monomer, ethylene,vinyl aromatic monomer divided by the calculated amount of triads havingthe same sequence as determined by Bernoullian statistical modeling isfrom 6 to 9.5.
 5. The highly alternating interpolymer according to claim4, wherein not less than 57% of the ethylene and vinyl aromatic monomeravailable to form triads, form triads having the sequence vinyl aromaticmonomer, ethylene vinyl aromatic monomer and less than 10% of themonomer available form vinyl aromatic monomer diads.
 6. The highlyalternating interpolymer according to claim 5, wherein the vinylaromatic monomer is present in an amount from 40 to 70 weight % of thepolymer.
 7. The highly alternating interpolymer according to claim 6,wherein the vinyl aromatic monomer is styrene.
 8. The highly alternatinginterpolymer according to claim 7, having a ¹³C NMR spectrum accordingto FIG.
 1. 9. A process for preparing the highly alternatinginterpolymer according to claim 1, comprising contacting a monomermixture comprising from 70 to 30 weight % of a C₈₋₁₂ vinyl aromaticmonomer and from 30 to 70 weight % of ethylene with a catalystcomprising a phosphinimine compound of the formula: L′((R¹)₃P═N)—M—L₂wherein each R¹ is independently selected from the group consisting ofC₃₋₆ alkyl radicals, L′ is anionic ligand having up to 50 C, H, O, N, Siand P atoms and M is selected from the group consisting of Ti, Zr andHf, and each L is independently selected from the group consisting of ahalogen atom, a hydrogen atom, a C₁₋₁₀ alkyl radical, a C₁₋₁₀ alkoxideradical, and a C₆₋₁₀ aryl oxide radical, and at least one activatorselected from the group consisting of: (i) a mixture comprising complexaluminum compound of the formula R² ₂AlO(R²AlO)_(m)AlR² ₂ wherein eachR² is independently selected from the group consisting of C₁₋₂₀hydrocarbyl radicals and m is from 3 to 50, and a hindered phenol toprovide a molar ratio of Al:hindered phenol from 2:1 to 5:1; (ii) ionicactivators selected from the group consisting of: (A) compounds of theformula [R³]⁺[B(R⁴)₄]⁻ wherein B is a boron atom, R³ is a cyclic C₅₋₇aromatic cation or a triphenyl methyl cation and each R⁴ isindependently selected from the group consisting of phenyl radicalswhich are unsubstituted or substituted with from 3 to 5 substituentsselected from the group consisting of a fluorine atom, a C₁₋₄ alkyl oralkoxy radical which is unsubstituted or substituted by a fluorine atom;and a silyl radical of the formula —Si—(R⁵)₃; wherein each R⁵ isindependently selected from the group consisting of a hydrogen atom anda C₁₋₄ alkyl radical; and (B) compounds of the formula[(R⁸)_(t)ZH]⁺[B(R⁴)₄]⁻ wherein B is a boron atom, H is a hydrogen atom,Z is a nitrogen atom or phosphorus atom, t is 2 or 3, and R⁸ is selectedfrom the group consisting of C₁₋₈ alkyl radicals, a phenyl radical whichis unsubstituted or substituted by up to three C₁₋₄ alkyl radicals, orone R⁸ taken together with the nitrogen atom may form an aniliniumradical and R⁴ is as defined above; and (C) compounds of the formulaB(R⁴)₃ wherein R⁴ is as defined above; and (iii) mixtures of (i) and(ii); in an inert hydrocarbyl medium at a temperature from 20° C. to150° C. and a pressure from 15 psi to 15000 psi.
 10. The processaccording to claim 9, wherein R¹ is a C₃₋₅ branched alkyl radical. 11.The process according to claim 10, wherein the hindered phenol is aphenol substituted in the 2, 4 and 6 position by a C₂₋₆ alkyl radical.12. The process according to claim 11, wherein the molar ratio ofAl:hindered phenol is from 3.25:1 to 4.50:1.
 13. The process accordingto claim 12, wherein the hindered phenol is 2,6-di-t-butyl-4-ethylphenol.
 14. The process according to claim 13, L is selected from thegroup consisting of a hydrogen atom, a chlorine atom and a C₁₋₄ alkylradical.
 15. The process according to claim 14, wherein R² is a methylradical and m is from 10 to
 40. 16. The process according to claim 15,wherein the pressure is from 50 to 600 psi and the temperature is from60° C. to 120° C.
 17. The process according to claim 16, wherein L′ is aphosphinimine ligand.
 18. The process according to claim 17, wherein thecatalyst is a mixture of a phosphinimine compound, aluminum compound anda hindered phenol.
 19. The process according to claim 18, wherein themolar ratio of Al to transition metal is from 50:1 to 500:1.
 20. Theprocess according to claim 19, wherein M is Ti.
 21. The processaccording to claim 20, wherein L′ is the same as the other phosphinimineligand in the complex.
 22. The process according to claim 17, whereinthe catalyst is a mixture of a phosphinimine compound and an ionicactivator.
 23. The process according to claim 22, wherein the molarratio of transition metal to boron is from 1:1 to 1:3.
 24. The processaccording to claim 23, wherein the molar ratio of transition metal toboron is from 1:1.05 to 1:1.20.
 25. The process according to claim 24,wherein M is Ti.
 26. The process according to claim 25, wherein theionic activator is tritylborate.
 27. The process according to claim 26,where in L′ is the same as the other phosphinimine ligand in thecompound.
 28. The process according to claim 17, wherein the catalystsystem is a mixture of a phosphinimine compound, aluminum compoundtogether with a hindered phenol and an ionic activator to provide amolar ratio of transition metal:Al:boron from 1:20:1 to 1:120:3.
 29. Theprocess according to claim 28, wherein the catalyst system has a molarratio of Ti:Al:boron from 1:30:1 to 1:45:1.5.
 30. The process accordingto claim 29, wherein the ionic activator is tritylborate.
 31. Theprocess according to claim 30, wherein M is Ti.
 32. The processaccording to claim 31, where in L′ is the same as the otherphosphinimine ligand in the compound.
 33. The process according to claim16, wherein L′ is a siloxy ligand.
 34. The process according to claim33, wherein the catalyst is a mixture of a phosphinimine compound and amixture comprising aluminum compound and a hindered phenol.
 35. Theprocess according to claim 34, wherein the molar ratio of Al totransition metal is from 50:1 to 500:1.
 36. The process according toclaim 35, wherein M is Ti.
 37. The process according to claim 36, wherein L′ is tri- t-butyl siloxy.
 38. The process according to claim 33,wherein the catalyst is a mixture of a phosphinimine compound and anionic activator.
 39. The process according to claim 38, wherein themolar ratio of transition metal to boron is from 1:1 to 1:3.
 40. Theprocess according to claim 39, wherein the molar ratio of transitionmetal to boron is from 1:1.05 to 1:1.20.
 41. The process according toclaim 40, wherein M is Ti.
 42. The process according to claim 41,wherein the ionic activator is tritylborate.
 43. The process accordingto claim 42, wherein L′ is tri- t-butyl siloxy.
 44. The processaccording to claim 33, wherein the catalyst system is a mixture of aphosphinimine compound, aluminum compound together with a hinderedphenol and an ionic activator to provide a molar ratio of transitionmetal:Al:boron from 1:20:1 to 1:120:3.
 45. The process according toclaim 44, wherein the catalyst system has a molar ratio of Ti:Al:boronfrom 1:30:1 to 1:45:1.5.
 46. The process according to claim 45, whereinthe ionic activator is tritylborate.
 47. The process according to claim46, wherein M is Ti.
 48. The process according to claim 47, wherein L′is tri- t-butyl siloxy.
 49. The process according to claim 16, whereinL′ is an amide ligand.
 50. The process according to claim 49, whereinthe catalyst is a mixture of a phosphinimine compound along withaluminum compound and a hindered phenol.
 51. The process according toclaim 50, wherein the molar ratio of Al to transition metal is from 50:1to 500:1.
 52. The process according to claim 51, wherein M is Ti. 53.The process according to claim 52, wherein L′ is 2,2,6,6-tetra methylpiperidinyl.
 54. The process according to claim 49, wherein the catalystis a mixture of a phosphinimine compound and an ionic activator.
 55. Theprocess according to claim 54, wherein the molar ratio of transitionmetal to boron is from 1:1 to 1:3.
 56. The process according to claim55, wherein the molar ratio of transition metal to boron is from 1:1.05to 1:1.20.
 57. The process according to claim 56, wherein M is Ti. 58.The process according to claim 57, wherein the ionic activator istritylborate.
 59. The process according to claim 58, wherein L′ is2,2,6,6-tetra methyl piperidinyl.
 60. The process according to claim 49,wherein the catalyst system is a mixture of a phosphinimine compound,aluminum compound together with a hindered phenol and an ionic activatorto provide a molar ratio of transition metal:Al:boron from 1:20:1 to1:120:3.
 61. The process according to claim 60, wherein the catalystsystem has a molar ratio of Ti:Al:boron from 1:30:1 to 1:45:1.5.
 62. Theprocess according to claim 61, wherein the ionic activator istritylborate.
 63. The process according to claim 62, wherein M is Ti.64. The process according to claim 63, wherein L′ is 2,2,6,6-tetramethyl piperidinyl.